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arXiv 1204.0509cond-mat.mtrl-sciphysics.comp-ph
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$G_0W_0$近似下的定量分子轨道能

Quantitative Molecular Orbital Energies within a $G_0W_0$ Approximation

Sahar Sharifzadeh, Isaac Tamblyn, Peter Doak, Pierre T. Darancet, Jeffrey B. Neaton

摘要:

利用多体微扰理论在$G_0W_0$近似下,对苯、噻吩和(1,4)二氨基苯三种气相分子的电离势(IP)、电子亲合势(EA)和基本能隙进行了计算,并与实验结果进行了比较.我们研究了IP的依赖于用于建立介电函数和自能量的未占用状态的数量,以及介电函数平面波截止。我们发现,一个有效的完成策略近似的未占用的子空间,和收敛的介电函数动能截止,计算的IP和EA是在良好的定量协议与现有的实验(在0.2 eV内),表明一个一次性的$G_0W_0$的方法可以非常准确地计算添加/去除能量的小有机分子。我们的研究结果表明,一个足够的介电函数动能截止可能是限制步骤广泛应用的$G_0W_0$更大的有机系统。

英文摘要:

Using many-body perturbation theory within the $G_0W_0$ approximation, we explore routes for computing the ionization potential (IP), electron affinity (EA), and fundamental gap of three gas-phase molecules -- benzene, thiophene, and (1,4) diamino-benzene -- and compare with experiments. We examine the dependence of the IP on the number of unoccupied states used to build the dielectric function and the self energy, as well as the dielectric function plane-wave cutoff. We find that with an effective completion strategy for approximating the unoccupied subspace, and a converged dielectric function kinetic energy cutoff, the computed IPs and EAs are in excellent quantitative agreement with available experiment (within 0.2 eV), indicating that a one-shot $G_0W_0$ approach can be very accurate for calculating addition/removal energies of small organic molecules. Our results indicate that a sufficient dielectric function kinetic energy cutoff may be the limiting step for a wide application of $G_0W_0$ to larger organic systems.

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